docs: def annotate_rule_violation(self, rule: ValidationRule) -> None:
          """
          Takes note of a rule validation failure by collecting its error message.
  
          :param rule: Rule that failed validation.
          :type rule: ValidationRule
          :return: None
          """
          if self.errors.get(rule.label) is None:
              self.errors[rule.label] = []
          self.errors[rule.label].append(rule.get_error_message())